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A hot-water pipe at 80°C is losing heat to the surrounding air at 5°C at a rate of 2200 W. Determine the rate of entropy generation in the surrounding
A horizontal, insulated cylinder has a frictionless piston held against stops by an external force of 500 kN.
A homeowner is trying to decide between a high efficiency natural gas furnace with an efficiency of 97 percent and a ground-source heat pump with a COP of 3.5.
A hollow steel sphere with a 2-ft inside diameter and a 0.1-in. thick wall contains water at 300 lbf/in 2, 500 F.
A house should be heated by a heat pump, ß' = 2.2, and maintained at 20oC at all times. It is estimated that it looses 0.8 kW per degree the ambient is lower
A house is maintained at 25°C in winter by electric resistance heaters. If the outdoor temperature is 2°C, the second-law efficiency of the resistance heaters.
A house is maintained at 1 atm and 24°C, and warm air inside a house is forced to leave the house at a rate of 150 m3/h as a result of outdoor air
A house is losing heat at a rate of 4500 kJ/h per °C temperature difference between the indoor and the outdoor temperatures. Express the rate of heat loss
A house is heated by an electric heat pump using the outside as the low-temperature reservoir.
A heat pump heats a house in the winter and then reverses to cool it in the summer. The interior temperature should be 20°C in the winter and 25°C in the summer
A heat pump has a coefficient of performance that is 50% of the theoretical maximum. It maintains a house at 20°C, which leaks energy of 0.6 kW per degree
A heat pump cycle is executed with R-134a under the saturation dome between the pressure limits of 1.8 and 0.2 MPa.
The house gains 0.6 kW per degree temperature difference to the ambient and the heat pump coefficient of performance is 60% of the theoretical maximum
A heat pump receives heat from a lake that has an average winter time temperature of 6°C and supplies heat into a house having an average temperature of 27°C
A heat pump that operates on the ideal vapor compression cycle with refrigerant-134a is used to heat water from 15 to 45°C at a rate of 0.12 kg/s.
A heat pump operates on the ideal vapor compression refrigeration cycle with R-134a as the working fluid between the pressure limits of 0.32 and 1.2 MPa
A heat pump is used to heat a house and maintain it at 24°C. On a winter day when the outdoor air temperature is -5°C, the house is estimated to lose
A heat pump is a device that absorbs energy from the cold outdoor air and transfers it to the warmer indoors
A heat pump with a COP of 3.2 is used to heat a perfectly sealed house (no air leaks). The entire mass within the house (air, furniture, etc.)
A heat pump with a COP of 2.8 is used to heat an air-tight house. When running, the heat pump consumes 5 kW of power
A heat pump with a COP of 2.5 supplies energy to a house at a rate of 60,000 Btu/h. Determine
A heat pump with a COP of 2.4 is used to heat a house. When running, the heat pump consumes 8 kW of electric power
A heat pump used to heat a house runs about one third of the time. The house is losing heat at an average rate of 22,000 kJ/h
A heat exchanger is incorporated into an ideal air-standard refrigeration cycle, as shown in Fig.
A hair dryer is basically a duct of constant diameter in which a few layers of electric resistors are placed.